Microscopy Techniques in Cell Investigation

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary purpose of vital examination in cell microscopy?

To enhance the separation power of the microscope

To examine living cells without damaging them (correct)

To utilize high levels of harmful dyes for clarity

To analyze dead cells using stains

Which type of microscope is specifically mentioned as being used in vital examinations?

Transmission electron microscope

Phase-contrast microscope (correct)

Fluorescence microscope

Scanning probe microscope

What is a significant characteristic of the phase-contrast microscope?

It provides 3D images using holography.

It enhances the contrast between various cell parts without staining. (correct)

It increases the separation power of the microscope.

It uses fluorescent dyes for staining cells.

Which technique is used to create differences in light intensity in a phase-contrast microscope?

Converting phase differences in light Signup and view all the answers

What is the role of the calcite or quartz plates in interference microscopy?

To enhance light clarity and contrast Signup and view all the answers

Why are harmless dyes like neutral red used in vital examination?

To prevent the cell from dying during examination Signup and view all the answers

Which of the following statements is accurate regarding the phase-contrast microscope?

It allows for the examination of live cells without staining. Signup and view all the answers

Which examination method utilizes fixation as part of its analysis?

Centrifugation Signup and view all the answers

What is the limitation of normal light microscopes regarding object visibility?

They cannot properly resolve objects closer than 0.2 μm. Signup and view all the answers

Which parameter increases when the objective of a microscope is moved closer to the object?

Angular resolution Signup and view all the answers

How is the magnification of a microscope calculated?

Ocular x Objective Signup and view all the answers

What type of light source is used in fluorescence microscopes?

Mercury vapor bulbs Signup and view all the answers

Which of the following describes the process of fluorescence in microscopy?

Fluorescent substances absorb shorter wavelengths and re-emit longer wavelengths. Signup and view all the answers

What is the smallest size of objects that can be examined with a fluorescence microscope?

0.1 μm Signup and view all the answers

Why are the optical parts of fluorescence microscopes often made of quartz?

Quartz does not absorb ultraviolet light. Signup and view all the answers

Which of the following accurately describes the principle behind fluorescence microscopy?

A filter allows only emitted light from stained objects to pass through. Signup and view all the answers

What is the primary purpose of differential velocity centrifugation?

To isolate particles according to their settling velocities Signup and view all the answers

Which component is most commonly used in Rate-Zonal centrifugation?

Sucrose solution Signup and view all the answers

What dictates the movement of particles in Rate-Zonal centrifugation?

The mass and density difference between the particles and the sucrose Signup and view all the answers

Which method should be used if organelles have similar mass and density?

Equilibrium density gradient centrifugation Signup and view all the answers

How is the bottom sediment obtained during differential velocity centrifugation?

By removing the supernatant after each centrifugation step Signup and view all the answers

What factor does Rate-Zonal centrifugation NOT consider when separating particles?

Presence of other organelles Signup and view all the answers

What happens to similar mass and density organelles after differential velocity centrifugation?

They cannot be separated and require further centrifugation methods Signup and view all the answers

What is a key characteristic of equilibrium density gradient centrifugation?

It separates particles based on their density Signup and view all the answers

What is the defining capability of totipotent stem cells?

They can generate a fully-functional living organism. Signup and view all the answers

Which type of stem cell is characterized by the ability to differentiate into nearly all cell types derived from the three germ layers?

Pluripotent stem cells Signup and view all the answers

What distinguishes multipotent stem cells from pluripotent stem cells?

Multipotent stem cells can differentiate into closely related cell types. Signup and view all the answers

Which type of stem cell can only produce its own specific cell type but possesses self-renewal capabilities?

Unipotent stem cells Signup and view all the answers

What is a key feature of oligopotent stem cells?

They can only differentiate into a few specific cell types. Signup and view all the answers

What is the main purpose of sucrose solutions in centrifugation?

To create a density gradient for separation by mass Signup and view all the answers

Which ions are primarily responsible for the density gradient in cesium chloride solutions during ultracentrifugation?

Cs+ ions Signup and view all the answers

At what approximate density difference does the bottom of the cesium chloride tube become denser than the top?

0.02 g/ml Signup and view all the answers

Which molecule has the highest density according to the provided data?

RNA Signup and view all the answers

What is the first step in the classical applications of recombinant DNA technology?

Cutting the desired DNA fragments using restriction enzymes Signup and view all the answers

What happens to protein molecules when exposed to cesium chloride ions during centrifugation?

They have a negligible binding with Cs+ ions. Signup and view all the answers

Which of the following is NOT a method used in rDNA technology?

Sonication Signup and view all the answers

Why do the densities of proteins, DNA, and RNA in the cesium chloride solution differ from their densities in cells?

CsCl ions bind to them at different rates, increasing their density. Signup and view all the answers

Study Notes

Cell Investigation Methods

Vital Examination is the microscopic examination of living cells in a liquid medium without harming them.
Phase-Contrast Microscope increases the contrast between different parts of the cell by converting phase differences in light passing through into differences in light intensity.
Interference Microscope uses calcite or quartz plates in front of the condenser to create contrast.
Dark Field Microscopy illuminates the sample from the sides, making it appear bright against a dark background.
Fluorescence Microscope utilizes fluorescent substances that absorb light of a certain wavelength and re-emit it at a longer wavelength, allowing for examination of stained objects.
Light Microscope uses visible wavelengths between 0.4 μm (400 nm) and 0.7 μm (700 nm) for observation.
Magnification of a microscope is calculated by multiplying the magnification of the ocular lens by the magnification of the objective lens.

Centrifugation Methods

Differential-Velocity Centrifugation separates organelles or particles of different sizes and densities based on their settling velocities.
Rate-Zonal Centrifugation separates particles based on their mass by adding the homogenate to a centrifuge tube containing a sucrose solution gradient.
Equilibrium Density Gradient Centrifugation separates particles based on their density by using a cesium chloride solution gradient.
Protein has a density of 1.3 g/ml, DNA has a density of 1.6-1.7 g/ml, and RNA has a density of 1.75-1.85 g/ml.

Recombinant DNA Technology

Recombinant DNA technology involves the production of genes from an organism (cloning) and their use for various purposes.
Classical Applications of rDNA technology involve four stages:
- Cutting DNA fragments using restriction endonucleases.
- Transferring fragments to a suitable vector.
- Replication of the fragment-vector complex in a host organism.
- Selection of organisms carrying the desired gene.

Stem Cells

Totipotent Stem Cells can differentiate into both embryonic and extraembryonic tissues.
Pluripotent Stem Cells differentiate into nearly all cell types derived from the three germ layers (endoderm, ectoderm, and mesoderm).
Multipotent Stem Cells differentiate into a limited number of cell types within a related family.
Oligopotent Stem Cells differentiate into only a few cell types.
Unipotent Cells can only produce their own cell type but have the property of self-renewal.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Explore various microscopy methods used for cell examination in this quiz. You'll encounter techniques such as vital examination, phase-contrast microscopy, and fluorescence microscopy, each serving unique purposes in cellular analysis. Test your knowledge on how these methods impact the observation of living cells.